Method of manufacturing a cutter disk



April 2, 1957 R. w. HYDE 2,787,174

METHOD OF MANUFACTURING A CUTTER DISK Filed Dec. 14, 1955 fijfum A1TOENEYS.

METHGD OF MANUFACTURING A CUTTER DISK Robert W. Hyde, incinnati, Ohio,assiguor, by mesne assignments, to American Radiator & Standard SanitaryCorporation, New York, N- Y., a corporation of Delaware ApplicationDecember 14, 1953, Serial No..397 ,984

3 Claims. (Cl. 76-.-.-104) This invention is directed to a cutter discand the method of manufacturing the same. -The cutter disc hasparticular utility in garbage disposal units of the type disclosed in mycopending patent application Serial No. 392,873, filed November 18,1953.

The garbage disposal unit of my copending patent application operatesnpon the principle of subjecting food waste to the cutting action of aspinning disc which has a plurality of teeth extending upwardly from theupper surface thereof. The disc is mounted for rotation about verticalaxis and is disposed at'the lower end of a casing, which, with the disc,defines the comminuting chzufnber of the disposal unit. inside of thecasing a pair of vanes which are disposed diametrically opposite to oneanother, overhang the outer edge of the disc. The purpose of the vanesis to prevent food waste whic is on the spinning disc from attaining therotational speed of the disc so as to maintain relative motion betweenthe food waste and the cutter disc. The vanes also serve to direct foodwaste which is on the outer edge of the spinning disc downwardly andinwardly from the inner wall of the casing onto .the spinning disc.'Thus, contrary to the accepted practice, the disposal unit of thecopending application cuts up or comminutes the food waste by means of,a dynamic, spinning element, and utilizes static or vane-like elementsto direct the food waste toward the cutting element. In the past, therelationship has been the reverse. s oecalled hammers, vanes or ribsmounted upon a spinning impeller have been used to forcibly throw ordirect food waste against stationary cutting teeth formed as a part of,or mounted upon, a. casing surrounding the impeller.

in the type of operation disclosed in my copending application, theefficiency of the unit is dependent upon the effectiveness of the cutterteeth which are on the spinning disc. Their effectiveness, of course, isdirectly related to their sharpness and. their ability to hold an edge.Accordingly the primary objective of the present invention is to provide"a method of manufacturing a highly improvedcutting disc havingexceedingly sharp cutting teeth which are adapted to maintain theirsharpness over prolonged and hard use.

A further objective has been to provide a cutter disc of the typedescribed which can be manufiactured at low cost utilizing readilyavailable material and production line techniques.

ther objects and advantages will be readily apparent to those s tilledin the art from the following detailed description of the drawings inwhich:

Figure l is a top plan view illustrating a cutter disc made inaccordance with the techniques of the present method.

Figure 2 is a fragmentary cross sectional View taken on the line 2,-2 ofFigure 1 illustrating the first step in the manufacture of the presentcutter disc,

Figure 3 is a diagrammatic view, in perspective, illushired StatesPatent 2,787,174 "i iPatented Apr. 2, 1957 ICC 2 trating the meansutilized in-the second step of the method.

Figure 4 is a view similar to Figure 2 showing the tooth at thecompletion of the second step in the method.

Figures 5, 6. and 7 are views similar to Figure 4'illu-s trating threeaddition'alsteps in the method, Figure 7 showing a finished tooth.

in general the cutter disc, which is indicated 'at 10 in Figure 1,consists of a'oircular plate having an aperture 11 in the center thereofby whichit may be-affixed-t-o the drive shaft of a garbage disposalunit. A flat 12 is formed in aperture 11 tokey it to the shaft. Thecentral area of the disc preferably is depressed' with respect to theplane of the upper surface'of the disc to provide a circular boss 13 atthe-underside thereof which seats on top of a packing gland in thedisposal unit. Preferably, the under surface of the boss 13 is polishedto reduce wear between the disc and the packing gland.

A plurality of substantially"V-shaped teeth or barbs 14- extend from theupper surface of the disc. These teeth may 'be disposed in a randompattern in the annular area of the disc between the depressed centralarea and the outer edge. It is preferred, however, that the teetl areoriented so that they either present the apex of their rough, V-shape ora sideedge thereof in the direction of the rotation of the installeddisc. The disc shown also has a plurality of radially disposed slitssuch as those indicated at 15 which are cut in the outer edge thereof tomake it possible to strike downwardly areas ahead of the slits in thedirection of rotation of the discs to expose shearing edges at thetopand outer ends of the slits. The exact configuration and purpose of theslits 15 is set forth in detail in the copending patent application referred to above and for this reason is not discussed here. Briefly,however, the edges provided .by the slits 15 cooperate with a shearingring in the disposal unit, the edges and ring resulting in unifQImparticle size in the comminuted material discharged from h Unit.

The present invention concerns primarily the formation and shape of theteeth which are indi ated at 14. The end sought is to provide knife-likesharp edges on thecutter teeth which are elfective to rapidly reduce theparticle size of food waste by cutting the waste into tiny bits andwhich are sufficiently hard and tough to not show appreciable wear overa lifetime of ordinary domestic use.

The preferred plate material for forming the cutter disc is .125 inchthick. The material currently is used for the manufacture of automobilebumpers, and therefore is readily available. The metal is identified asS. A. E. 950.

The cutter disc is first blanked out to produce a circular plate fromthe stock material. The central boss 13 and the aperture 11 then may beformed by conventional stamping and dieing techniques. At this time, theradial slits 15 may 'be formed and the edge of the plate adjacent to theslits bent down as disclosed in the copending application. Theseoperations are carried out at the upper side of the disc, The first stepin the present method to form the cutter teeth isto punch the reverse or.underside of the plate with a plurality of V-shaped punches which arearranged in thev pattern of the teeth illustrated in Figure 2. Thisoperation initially forms the teeth or barbs 14. The condition of atooth after the punching operation is illustrated in Figure 2. At thistime, the tooth or barb is on a slant and. extends above the uppersurface of the disc approximately .G9-.l inch. In the next step of themethod, the teeth are scrubbed over by means of a tool which is pressodagainst the. face of the disc while the tool is. being rotated at highspeed in he ir cti that he cu ter disc ota es. when t ,i

"being used in disposal Before this is done, however, the plate materialis annealed by a heat treatment to soften it to approximately Rockwell B74. The annealing may be done'at 1240" F. for eight hours and the blankdisc cooled slowly from this temperature over a period of eight hours.

The preferred means for scrubbing over the teeth is shown in Figure 3.The tool consists of a heavy circular plate 16 upon which a plurality ofhalf round, tool steel bars 17 are radially disposed. In the presentinstance,

four such bars, mounted at equally spaced points circumferentially ofthe plate are employed. The annealed disc is fastened rigidly in placeand the rapidly turning plate 16 moved in toward the face of the disc.During such movement the plate 16 is maintained in parallel relation tothe cutter disc with its axis of rotation in alignment with the centralaxis of the disc. The half round bars 17 on plate 16 upon being pressedinwardly toward the disc swage or scrub over the edges of the barbs sothat they appear as shown in Figure 4, having a rather long marginal lipportion 18 overhanging in the direction of rotation of the plate 16. Thebars 17 should be applied sufiiciently long and under enough pressure toreduce the distance that the teeth extend above the surface of the discfrom approximately .09.1 inch to approximately .03-.O4 inch. Theoverhanging lip 18 at this time is rounded and would not serve as acutting edge.

In the next step of the operation, the barbs or teeth are flattened backinto the plate by a die which engages the upper surfaces thereof. Thisalso is carried out under considerable pressure, sufiicient at least toswage over and slightly round the edges 19 of the plate material beneaththe overhanging lips 18. It also serves to flatten out slightly therounded edges 19. The condition of a tooth under these circumstances isillustrated in Figure 5. Preferably, the teeth are flattened to a pointwhere they extend only approximately .005 above the upper surface of thedisc.

After the flattening operation, the barbs or teeth are surface ground toreduce the extent that they extend above the upper face of the disc toapproximately .002 maximum. The effect of the grinding is to change theoverhanging, rounded lips 18 into exceedingly sharp knife-like edgessuch as the one indicated at 20. At this time the upper surface of thecutter disc is substantially planar. In the next step, the barbs areagain punched outwardly, using the same technique by which the barbswere formed in the first step. When finished, the teeth should be abovethe upper surface of the disc approximately .09.1 inch. The entire discis then case-hardened to approximately .0l-.0l5 deep, being quenched, tofilehardness preferably as hard as Rockell 88 using the -N scale.

As the last step in the method, the disc may be ltruedup by grinding theouter edge to remove burrs and other small irregularities. The face ofthe boss 13 may be polished at the same time, care being exercised toinsure that it is parallel with the upper surface of the disc.

The scrubbing and grinding to which the teeth are subjected result inconsiderably less than precisely formed cutting edges. As shown inFigure 2, the edges are irregular or jagged. However, it is found thatthe unevenness of the edges increases, rather than decreases, theefficiency of the cutter disc in a disposal unit. By scrubbing over theteeth so that they overhang in the direction of rotation of the cutterdisc, surprisingly wide knife-like cutting edges are produced. Such wideedges, being file hard, are found to stand up and last exceedingly wellin the life tests to which discs made in accordance with the presentmethod have been subjected.

Having described my invention, I claim:

1. The method of manufacturing a cutter disc for use in a cuttingoperation in which said disc rotates in one direction only, said methodcomprising the steps of providing a circular plate made of metal whichis adapted to be annealed and subsequently case-hardened, punching theunderside of said plate to form a plurality of V-shaped barbs whichextend from the upper surface of said plate at an angle between ten andthirty degrees, the respective V-shaped barbs being oriented so thateither a side thereof or a point thereof is presented in the directionof the rotation of the disc when in use, annealing said plate,subjecting said barbs to the scrubbing action of a blunt tool which ispressed against said barbs while traveling in the direction of therotation of the disc when in use so as to form lips which overhang theedges of the baths in said direction, flattening said barbs back intothe plate so far as the overhanging lips permit, surface grinding theupper surface of said plate to sharpen said overhanging lips,re-punching said barbs as in the second step above, and case-hardeningsaid disc.

2. The method of manufacturing a cutter disc for use in a cuttingoperation in which said disc rotates in one direction only, said methodcomprising the steps of providing a circular plate made of metal whichis adapted to be annealed and subsequently case-hardened, forming aplurality of V-shaped barbs which extend from the upper surface of saidplate at an angle between ten and thirty degrees, annealing said plate,subjecting said barbs to the scrubbing action of a blunt tool which ispressed against said barbs while traveling in the direction of therotation of the disc when in use so as to form lips which overhang theedges of the barbs in said direction, flattening said barbs back intothe plate as far as the overhanging lips permit, grinding the uppersurface of said plate to sharpen said overhanging lips, re-forming saidbarbs as in the second step above, and case-hardening said disc.

3. The method of manufacturing a rotatable cutter disc having teeth.thereon which comprises the steps of providing a circular plate made ofmetal which is adapted to be annealed and subsequently case-hardened,punching the underside of said plate to form substantially V-shapedbarbs which extend from the upper surface of the plate at an angle ofbetween ten and thirty degrees, annealing said plate, subjecting saidbarbs to the scrubbing action of a blunt :tool which is presented tosaid barbs while it is traveling in the direction the cutter discrotates when in use to form a lip on each of said barbs which overhangsthe edge thereof, flattening each of said barbs back into the plate asfar as said overhanging lip permits, grinding said barbs to sharpen theoverhanging lips, re-punching said barbs as in the second step, andcase-hardening said disc to file-hardness.

4-. The method of manufacturing a rotatable cutter disc having teeththereon which comprises the steps of providing a circular plate made ofmetal which is adapted to he annealed and subsequently case-hardened,punching the underside of said plate to form substantially V-shapedbarbs which extend from the upper surface of the plate at at angle ofbetween ten and thirty degrees, annealing said plate, forming a lip oneach of said barbs which overhangs the edge thereof in the direction ofrotation of the disc, flattening said barbs back into the plate as faras the respective overhanging lips permit, grinding said barbs tosharpen said overhanging lips, re-punching said barbs as in the secondstep above, and case-hardening said disc to file hardness.

5. The method of manufacturing a cutter disc which comprises the stepsof providing a circular metal plate, punching the underside of saidplate to form substantially V-shaped barbs which extend from the uppersurface of said plate, forming an overhanging lip on each of said barbs,flattening said barbs into the plate as far as the respectiveoverhanging lips permit, grinding the upper surface of said plate tosharpen said overhanging lips, and rte-punching said barbs as in thesecond step above.

6. The method of manufacturing a rotatable cutter disc which comprisesthe steps of providing a circular metal plate, punching the underside ofsaid plate to form substantially V-shaped barbs which extend from theupper surface of said plate at an angle of between twenty and thirtydegrees, subjecting said barbs to the scrubbing action of a blunt toolto form an overhanging lip on each or said barbs, flattening said barbsinto the plate as far as the overhanging lips permit, grinding the uppersurface of said plate to sharpen said overhanging lips and repunchingsaid barbs as in the second step above.

7. The method of manufacturing a rotatable cutter disc having teeththereon which are oriented to present cutting edges in the directionsaid disc rotates when in use, said method comprising the steps ofproviding a circular plate made of a metal which is adapted to beannealed and subsequently case-hardened, punching the underside of saidplate to form substantially V-shaped barbs which extend angularly fromthe upper surface of said plate substantially in the direction said discrotates when in use, said V-shaped barbs being oriented so as to presenteither a flat side or a point thereof in said direction, annealing saidplate, subjecting said barbs to the scrubbing action of a blunt toolwhich is pressed against said barbs while rotating substantiallyparallel to the upper surface of said disc and in the direction ofrotation of the cutter disc when in use so as to form lips on said barbswhich overhang the upper surface of said disc in said direction,flattening said barbs back into the plate as far as said overhanginglips permit, surface grinding the flattened barbs to sharpen saidoverhanging lips, re-punching said barbs as in step two above, andcase-hardening said disc to file-hardness.

8. The method of manufacturing a rotatable cutter disc having teeththereon which are oriented to present knife-like edges in the directionsaid disc rotates when in use, said method comprising the steps ofproviding a circular plate, forming substantially V-shaped barbs whichextend from the upper surface of said plate at an angle of between tenand thirty degrees, said V-shaped barbs being oriented so as to presenteither a fiat side or a point thereof in the direction said disc rotateswhen in use, forming lips on said barbs which overhang the upper surfaceof said disc in said direction of rotation thereof, flattening saidbarbs back into the plate as far as said overhanging lips permit,grinding the flattened barbs to sharpen said overhanging lips, andre-forming said barbs as in step two above.

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